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Microbiology > Weapons of Mass Infections > Flashcards

Weapons of Mass Infections Flashcards

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Biology 101 flashcards
1
Q

Primary Pathogens

A

-cause disease in healthy hosts

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2
Q

Opportunistic Pathogens

A

-cause disease only in compromised hosts or entry into unprotected sites
-generally do not cause trouble, but will take over if opportunity presents itself.

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3
Q

Infection

A

-when a pathogen or parasite enters/begins to grow on a host
-doesn’t imply overt disease
-some microbes can enter latent state during infection, prevent them from being found on culture

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4
Q

Pathogenicity

A

-organism’s ability to cause disease
-defined in terms of:
–infectivity (how easy it causes disease)
–virulence (how severe that disease is)
–specific genetic makeup of pathogen

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5
Q

Virulence

A

-relative ability of pathogen to cause disease
-measured with ID50 (infectious dose) & LD50 (lethal dose)

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6
Q

ID50

A

-# of pathogen cells or virions required to cause active infection in 50% of inoculated animals

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7
Q

LD50

A

-amount of an agent that kills 50% of animals in test group

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8
Q

Immunopathogenesis

A

-when immune response to a pathogen is contributing cause of pathology & disease

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9
Q

Infection Cycle

A

-route of transmission of an infectious organism
-horizontal transmission - from 1 organism to another in same generation
-vertical transmission - from mom to fetus

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10
Q

Steps to Pathogenesis

A
  1. Exposure to Pathogens
  2. Adherence to skin or mucosa
  3. Invasion through epithelium
  4. Multiplication; growth & production of toxins & virulence factors
  5. Toxicity or Invasiveness
  6. Tissue/Systemic damage

1-4 are infection process, 5-6 are disease process

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11
Q

To cause disease, all pathogens must:

A

-attach to our surfaces & tissues
-damage tissues to obtain nutrients & replicate
-avoid host immune responses

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12
Q

Virulence Factors

A

-encoded on virulence genes
-include toxins, attachment proteins, capsules, & other devices

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13
Q

Pathogenicity Islands

A

-most appear to have been horizontally transmitted via conjugation or transduction
-unique GC/AT ratio
-codon bias
-flanked by inverted repeats
-found only in certain strains

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14
Q

Adhesins

A

-recognize specific receptors
-specifically bind to receptors on cell surface
-glycoproteins or lipoproteins found of pathogen surface, enabling binding to host cells

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15
Q

Pili or Fimbriae

A

-hairlike appendages that attach to specific host cells
-Type I - adhere to carbs on host membranes, grow from outer membrane of gram - bacteria
-Type IV - involved in twitching motility, retractable, can drag itself around, grown from inner membrane of gram - bacteria

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16
Q

Nonpilus Adhesins

A

-bacterial also possess adhesins that are not pili
-examples:
–M protein in Strep pyogenes
–Pertactin in pertussis
–MAM7 in pseudomonas aeruginosa

17
Q

Why can some people be susceptible to infections?

A

-Immunocompetence: capacity to see & eliminate danger
-Receptor availability
-pathogens rely on specific surface receptors to recognize & bind
–differences in these from person to person

18
Q

Capsules

A

-forms thick coating outside plasma membrane & cell wall
-serves 2 important functions in bacterial pathogenicity
–no capsule, strain is not pathogenic
–sticky & contains specific receptors to facilitate attachment to host
–inhibits opsonization & phagocytosis

19
Q

Colonization

A

-growth of microorganisms after they’ve gained access to host tissues

20
Q

Invasiveness

A

-ability of pathogen to grow in host tissue @ densities that inhibit host function

21
Q

Septicemia

A

-bloodborne systemic infection

22
Q

Hyaluronidase

A

-breaks down host tissues

23
Q

Coagulase & Streptokinase

A

-manipulate clotting
-coagulase forms clots
-streptokinase breaks them down

24
Q

Exotoxins

A

-proteins produced & secreted by various types of bacteria
-kill host cells & unlock nutrients
-AB toxins, cytolysins, superantigens
-mostly gram +

25
Q

Endotoxins

A

-part of LPS of gram - bacgeria
-lipoteichoic acid on gram + cells
-hyperactive host immune systems to harmful levels
-mostly gram -

26
Q

Membrane Disruption (cytolysins)

A

-2 types of exotoxins disrupt host cell membranes
-pore forming proteins
-phospholipase enzymes

27
Q

Phospholipase enzymes

A

-hydrolyze phospholipids into fatty acids

27
Q

Pore-forming proteins

A

-insert themselves into membranes by binding cholesterol & membrane receptors

27
Q

Hemolysins

A

-lyse RBCs

27
Q

Leukocidins

A

-lyse WBCs

28
Q

AB exotoxins

A

-consist of 2 subunits that work together
-A subunit: toxicity associated factor
-B subunit: binds host cell, delivers A subunit

28
Q

Endotoxin (LPS)

A

-made only by gram - bacteria
-LPS composed of lipid A (endotoxin), core glycolipid, and polysaccharide chain (o antigen)
-form on outer membrane
-as bacteria die, release MAMP that binds to macrophages/B cells
–triggers massive cytokine release, leading to fever, shock, inflammation, & death

29
Q

Lipid A

A

-endotoxin part of LPS
-less toxic than exotoxins
-less immunogenic
-local infections, diarrhea, vomiting & fever
-immunopathogenic: sends immune system in spiral

30
Q

Secretion systems

A

-facilitate cellular activities
-forms channels through membranes
-secretes proteins directly outside cells into env. or injects into host cell

31
Q

Type II Secretion System (T2SS)

A

-modification of type IV pilus biogenesis
-extend & retract, like pili
-proteins get secreted into periplasm, then folded & secreted via outer membrane pore

32
Q

Type III Secretion

A

-injection machine
-insert own receptors into target cells
-reenginerred flagellar synth mech
-triggered by cell-cell contact
-inject toxins (effectors) into euk. cells

33
Q

Effector proteins

A

-proteins that have a function that will help bacteria manipulate host to it’s advantage

34
Q

Type IV Secretion

A

-evolutionary modification of conjugation pilus that secretes proteins only, or proteins + DNA
-allows bacterial pathogens to secrete proteins directly from cytoplasm or periplasm

Microbiology (3 decks)

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